As a conventional surface-enhanced Raman scattering element, one equipped with a minute metal structure adapted to generate surface-enhanced Raman scattering (SERS) has been known (see, for example, Patent Literature 1 and Non Patent Literature 1). In such a surface-enhanced Raman scattering element, when a sample to be subjected to Raman spectroscopic analysis is brought into contact with the minute metal structure and is irradiated with excitation light in this state, surface-enhanced Raman scattering occurs, whereby Raman scattering light enhanced by about 108 times, for example, is released.
Meanwhile, for example, Patent Literature 2 discloses a trace material detection element comprising a substrate, a plurality of minute protrusions formed on one surface of the substrate, and metal layers formed on the one surface of the substrate and upper faces of the minute protrusions. In particular in this trace material detection element, the metal layer formed on the upper faces of the minute protrusions and the metal layer formed on the one surface of the substrate are out of contact with each other, so as to form an interstice on the order of 5 nm to 10 m therebetween.